1. Field of the Invention
The present invention relates to a rotation device, a method for transferring a worn article, and a method for folding a web.
2. Background of the Invention
Japanese Laid-Open Patent Publication No. 63-317576, for example, discloses a movement of a plurality of pads rotating about a predetermined axis while each of the pads changes its velocity, during a process of producing a worn article or a web (a continuous material). Japanese National Phase PCT Laid-Open Publication No. 2000-514024 discloses a material engagement member reciprocating in a direction parallel to a rotation axis of a drum.
When each of the pads is supported by a bearing, the same number of bearings as the number of pads are required so that the velocities of the pads can be changed individually, thereby increasing the size and/or complexity of the device.
In view of the problem in the prior art, it is an object of the present invention to provide a rotation device having a simple structure and being capable of providing a complicated movement. It is also an object of the present invention to provide a method for transferring a worn article, a method for folding a web and a device for folding a web that can suitably employ the rotation device, and a disposable worn article produced by using the same.
In order to achieve the objects set forth above, a first rotation device of the present invention includes: an endless guide; a plurality of moving sections that slide while being guided by the guide; and a rotation member that allows the guide to rotate about an axis. In addition, the plurality of moving sections are arranged in the rotation allowance direction of the rotation member; and the plurality of moving sections can slide in the direction of rotation of the rotation member or in the opposite direction by being guided by the guide.
A second rotation device of the present invention includes: a plurality of guides; a plurality of moving sections that slide while being guided by the plurality of guides; and a rotation member that allows the plurality of guides to rotate about an axis. Furthermore each of the moving sections is guided by at least one of the guides; and the plurality of guides is provided about the axis so as to be arranged in the rotation allowance direction of the rotation member while surrounding the axis, so that the plurality of moving sections can slide in the direction of rotation of the rotation member or the opposite direction.
As a rotational force having a predetermined velocity curve is applied to the moving sections, the rotation member rotates at a high velocity along with the rotation of the moving sections. Meanwhile, each moving section rotates with respect to the guide at a low relative velocity. In this way, the friction between the moving sections and the guide is significantly reduced, thereby improving the durability of the device.
Ideally, the rotation member is capable of an unlimited rotation, and may be a ball bearing or a roller bearing including a rolling element such as a ball or a roller.
The guide may be any type of guide as long as it allows the sliding movement of the moving sections in a direction including a component of the rotation allowance direction of the rotation member. The term xe2x80x9cendless guidexe2x80x9d as used herein refers to not only a generally completely ring-shaped guide, but also to those having slight gaps in the circumferential direction, or even to those obtained by arranging guide elements, which together form one guide, so as to be spaced apart from one another at a predetermined interval. Moreover, the guide elements may overlap with one another as viewed in the axial direction. The phrase xe2x80x9cin a direction including a component of the rotation allowance direction of the rotation memberxe2x80x9d as used herein means that a guide element may be provided in an inclined direction. The guide element may be a rail or a groove.
In the second rotation device of the present invention, the phrase xe2x80x9ca plurality of guidesxe2x80x9d means that the guides are spaced apart from one another in the direction of rotation or in the axial direction to such a degree that a moving section cannot move from one guide to another.
Where one moving section moves from one of a plurality of guide elements to another, the plurality of guide elements together form one guide.
In the present invention, it is preferred to provide a controller for controlling the moving velocity of the moving sections. Such a controller causes the moving sections to rotate at differing predetermined instantaneous velocities, thereby changing the pitch between the moving sections during rotation.
The term xe2x80x9cinstantaneous velocityxe2x80x9d as used herein refers to a velocity in a minute period of time, meaning that each moving section rotates while changing its velocity depending on the rotational position thereof.
The present invention can be used with a rotation device as described in PCT International Publication WO01/44086, a method for transferring worn articles while changing the pitch thereof, a method for folding a web, or a device for folding a web.
A method for folding a web of the present invention is a method for folding a web by using a rotation device including a plurality of pads that rotate about a predetermined axis so as to continuously transfer the web. The method includes: supplying the web onto surfaces of the rotation device pads; rotating adjacent ones of the pads onto which the web has been supplied so as to change the interval therebetween to slacken a portion of the web between the adjacent pads, thereby folding the portion of the web; and releasing the web from the pads.
Such a folding method can be realized using the first or second rotation devices of the present invention. Other rotation devices such as that described in PCT International Publication WO01/44086 may be used in place of the rotation device including a plurality of pads.
A device for folding a web of the present invention is a device for folding a web to form a wall in a direction transverse to a web running direction. The device includes: a transfer member for forming a slack portion in the web in the running direction thereof while continuously transferring the web; and a member for folding the slack portion so as to form the wall.
The term xe2x80x9cwallxe2x80x9d as used in the present invention refers to a portion of a web or a sheet-like material that has been folded, regardless of whether the wall is laid down along the surface of the web or standing on the web.
In the folding device of the present invention, the xe2x80x9ctransfer memberxe2x80x9d may be any member including a plurality of transfer sections for transferring the web in the web running direction, wherein the transfer velocity of one of the transfer sections is set to be lower than that of another transfer section upstream of the one of the transfer sections so as to form a slack portion in a portion of the web between the upstream and downstream transfer sections.
In the present invention, it is preferred to provide a directioning member for defining the direction in which a slack portion is to be folded.
In the present invention, the term xe2x80x9cslack portionxe2x80x9d refers to a portion of a web on which no tension is applied.
In the present invention, it is preferred to provide a fold-holding section for maintaining the shape or condition of a folded portion obtained by folding the slack portion.